In current CSMA-CA scheme for IEEE 802.11 (WiFi) communications, a station (STA) delays its access to a medium for transmitting data by a determined back-off time, e.g., in microseconds (μsec). The back-off time is calculated by selecting a random number from a predetermined contention window size. A Markov Chain analysis of throughput using this formula for calculating the back-off time reveals that the peak throughput can be sustained at about 70% of the overall throughput in normal network conditions (acceptable density of STAs or transmissions). The contention window size is increased or decreased based on previous success or failure according to detection of collisions with other STA transmissions. An improved scheme for determining the back-off time that results in fewer collisions between STAs and higher overall throughput is favorable, such as for relatively large STA or transmission concentration.